Cmake project to Qt qmake project, problem with -msse3

I'm very new to Qt and Linux, but hopefully you could help to find a solution for the following problem.
I have a couple of complex Qt projects which are working fine. But now I want to use a CMake project (library for visual odometry) together with my other Qt projects (camera frame grabber, projects based on OpenCV...).

Therefore I used the following command to import all header and source files from the cmake project.
@qmake -project@

When I Run the project I got lots of errors, like:
/usr/lib/gcc/i686-linux-gnu/4.6/include/emmintrin.h:32: error: #error "SSE2 instruction set not enabled"
or
/usr/lib/gcc/i686-linux-gnu/4.6/include/pmmintrin.h:32: error: #error "SSE3 instruction set not enabled"

This is the place where the error occures in the emmintrin.h file:
@#ifndef SSE2

error "SSE2 instruction set not enabled"

#else@

I think thats because I haven't set the msse3 instruction, like it is done with the following code in the CMakeLists.txt file:
@# use sse3 instruction set
SET(CMAKE_CXX_FLAGS "-msse3")@